A century ago, Pope Pius X was Pope and there were fewer than 300 million Catholics. When the new Pope is installed in March, he will guide a flock of over 1.1 billion - nearly four times the size guided by Pius X.

Not only has the number increased, but also the church's diversity. In 1910, Europe was home to about two-thirds of all Catholics, and nearly nine-in-ten lived either in Europe (65%) or Latin America (24%), according to the World Christian Database. By 2010, only about a quarter of all Catholics (24%) were in Europe. The largest share (39%) were in Latin America and the Caribbean, according to a recent study by the Pew Research Center.

But the most rapid growth has occurred in sub-Saharan Africa, which today is home to about 171 million Catholics (16%), up from an estimated 1 million (less than 1%) in 1910 - an increase of more than 170-fold. There also has been rapid growth in the vast Asia-Pacific region, where 131 million Catholics (12%) now live, up from 14 million (5%) a century ago - an almost ten-fold increase.

Even in China, Catholics have experienced nearly a ten-fold increase - numbering between nine and twelve million today, up from slightly more than one million in 1910.

Spotlight on Catholics in China: An interview with an "underground" Catholic priest

According to a recent Pew Research study, a substantial number of Christians worship in independent, unregistered churches. These churches do not have legal status because they have not affiliated with one of the two officially approved associations. Unregistered independent Protestant churches, often referred to as “house churches,” meet in various venues including homes, rented facilities, businesses and even public places. Additionally, a substantial number of Catholics worship in unregistered congregations that refuse to join the Patriotic Catholic Association. A main point of contention is that the Association operates independently from Rome; for instance, it appoints bishops without the approval of the pope.

North America’s share of the global Catholic population has increased more slowly, from about 15 million (5%) in 1910 to 89 million (8%) as of 2010.

Though the Middle East and North Africa are the ancient cradle of Christianity, the Middle East-North Africa region is home to less than 1% of Catholics today, about the same as in 1910.

For more details on the study by the Pew Research Center's Forum on Religion & Public Life, see the following links:

Last week's arrests* of four people on suspicion of being Christian missionaries in the eastern Libyan city of Benghazi is an example of a fairly common government restriction on religion around the world.

In one-in-three countries worldwide (34%), some level of government limits proselytizing - sharing about one's faith in an attempt to get another person to join the faith - according to a recent study by the Pew Research Center.

Government limits on proselytizing vary greatly by region, as shown in the chart below. They are most common in the Middle East and North Africa, where 80% of countries impose limits. Sometimes restrictions are de facto rather than explicitly legal. In Egypt, for instance, proselytizing is not limited by law, but the U.S. State Department reports that "police have in the past detained or otherwise harassed those accused of proselytizing on charges of ridiculing or insulting the three 'heavenly religions' - Islam, Christianity, or Judaism - or inciting sectarian strife."

More than half the governments in Asia-Pacific (56%) impose restrictions on proselytizing. In Indonesia, for example, the government’s Guidelines for the Propagation of Religion bar most proselytizing, and Article 156 of the Criminal Code makes spreading heresy and blasphemy punishable by up to five years in prison. More than one-in-five (22%) European governments or government representatives imposed restrictions on proselytizing, including Greece, where the constitution and law forbid proselytizing. However, as of mid-2010, there were fewer reported cases where Greek police detained people for proselytizing.In sub-Saharan Africa, 19% of governments limit proselytizing. Sometimes these limitations do not specifically use the term "proselytizing." For example, Sierra Leone’s Constitution stipulates that “for the purposes of protecting the rights and freedoms of other persons,” there should be no “unsolicited intervention of the members of any other religion.” This could be taken to mean that members of one religion should not try to proselytize members of other religious groups.

Only 9% of countries in the Americas limit proselytizing. For instance, the government of Venezuela limits Venezuelan or foreign missionary groups from working in indigenous areas.

For background on proselytizing, see UN Special Rapporteur Heiner Bielefeldt's recent report to the UN General Assembly on the right to try to convert others by means of non-coercive persuasion. Also see previous Weekly Number Blogs noting that social hostilities are more than twice as high in countries that (a) limit conversion or (b) penalize apostasy.* The arrests were widely reported in the media, including the BBC, Reuters, Al Jazeera, USA Today, AP, Fox, the Guardian, and South Korea's Yonhap News. Those arrested include an Egyptian, a South African, a Korean and a Swede who was traveling on a U.S. passport.

As Chinese New Year begins on Feb. 10, 2013, some 640 million people of all ages are affiliated with religion in China.

Just three decades ago, few researchers even within mainland China knew whether religion had survived the Cultural Revolution (1966-1976) initiated by Chairman Mao Zedong. It is clear now, however, that religion not only survived but that hundreds of millions of Chinese today have some religious faith, according to recent studies by the Pew Research Center.

Nearly 300 million Chinese are affiliated with folk religions. Globally this means that more than seven-in-ten (73%) of the world’s folk religionists live in China.

Some 244 million people in China adhere to Buddhism, making China home to half (50%) of the world’s 488 million Buddhists.

China's 68 million Christians make China home to the world’s seventh-largest Christian population.

China's approximately 25 million Muslims constitute the world's 17th largest Muslim population, right after Saudi Arabia (# 16) and before Yemen (#18).

China has the world's second largest shares of people who belong to faiths in the “other religion” category (16%), many of whom are adherents of Taoism. The World Religion Database estimates there are more than 8 million Taoists worldwide.

The general consensus among scholars of religion in China is that religious affiliation has grown substantially during the past three decades. It is too soon to know, however, whether religion’s growth has peaked or will continue in the years ahead. Whichever turns out to be the case, the religious future of the world’s most populous country will have a major impact on religion in the decades ahead.

Additional information from the Pew Research Center's Forum on Religion & Public Life:

Recent events in Algeria, Burma, China, Egypt, Indonesia, Russia, Saudi Arabia and Syria - countries with very high government restrictions on religion - draw attention to a recent Pew Forum study that found social hostilities involving religion are substantially higher where national governments do not protect freedom of religion or belief. The study by the Pew Research Center's Forum on Religion & Public Life found that social hostilities are 4.6 times higher when the national government does not protect religious freedom. (See chart below.)

It may be that social hostilities contribute to high government restrictions, and vice versa.*

ongoing unrest directed toward the Egyptian government led by President Mohamed Morsi (protesters reportedly accuse Morsi of "concentrating too much power in his own hands and those of his Muslim Brotherhood");

* As noted in previous Pew Forum studies on religious restrictions, higher scores on the Government Restrictions Index are associated with higher scores on the Social Hostilities Index and vice versa. This means that, in general, it is rare for countries that score high on one index to be low on the other.